Display device, terminal device, light source device, and optical member

ABSTRACT

A display device comprising a light source and having an optical waveguide, a louver, an anisotropic scattering sheet, and a transmissive liquid crystal panel disposed along the path of light emitted from the light source. The light-restricting direction of the louver is tilted at an angle α from the Y-axis direction. The value of the angle α is set so that the arrangement direction of moiré created between the louver and the liquid crystal panel approaches the X-axis direction. A plurality of belt-shaped convex portions extending in the Y-axis direction are formed on the surface of the anisotropic scattering sheet, and are configured so that the scattering direction of the light has anisotropy. Specifically, scattering in the X-axis direction is increased, and scattering in the Y-axis direction is reduced. Moiré can thereby be reduced in a display device having increased directivity of the display.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a display device in which thedirectivity of the display is increased with respect to a specificdirection, to a terminal device provided with this display device, andto a light source device and optical member incorporated into theaforementioned display device.

2. Description of the Related Art

Due to recent advances in technology, display panels have been deployedin a range of devices that includes monitors, television sets, and otherlarge terminal devices; notebook-type personal computers, cashdispensers, vending machines, and other mid-sized terminal devices; andpersonal TVs, PDAs (Personal Digital Assistance: personal informationterminal), mobile telephones, mobile gaming devices, and other smallterminal devices that are used in a variety of locations. Because oftheir thin profile, light weight, small size, low energy consumption,and other advantages, display devices that use liquid crystals areparticularly common in terminal devices.

Among these terminal devices, small-to-medium-sized terminal devices arecharacteristically used not only in closed rooms under tight security,but also in public places. It then becomes important to keep displays ofprivate information and confidential information from being viewed by athird party. Particularly in recent years, occasions where privateinformation and confidential information are displayed have increased inconjunction with the development of terminal devices, and demand foreavesdropping prevention techniques is increasing. A display device inwhich the display can be viewed only by a user positioned in front or inanother specific direction, and eavesdropping from other directions isprevented by narrowing the range of angles in which the display isvisible has been proposed together with an eavesdropping-preventingoptical member applied to this display device (see Japanese Laid-OpenPatent Application 2003-131202, for example: hereinafter referred to asPrior Art 1).

FIG. 22 is a sectional view showing the anti-eavesdropping devicedisclosed in Prior Art 1. This anti-eavesdropping device is affixed tothe display surface of the display device and used. In this conventionalanti-eavesdropping device as shown in FIG. 22, a thin anti-glare layer1101 is provided, and a thin adhesive layer 1110 having hightranslucency is layered on and attached to the back surface of thisanti-glare layer 1101. A silicone adhesive layer 1120 is also providedto the surface of the anti-glare layer 1101, and a translucent thintranslucent layer 1130 is integrally bonded and layered via the siliconeadhesive layer 1120. The anti-glare layer 1101, the adhesive layer 1110,and the translucent layer 1130 are each in the form of a flexible sheetor film. The surface of the adhesive layer 1110 on the opposite sidefrom the anti-glare layer 1101 is a smooth, translucent attachmentsurface 1111 having a mirror finish, and is an attaching surface thatcan be detachably affixed to the display surface of the liquid crystaldisplay (not shown in the drawing) of an information display device.

The anti-glare layer 1101 is formed by integrating a plurality oftransparent silicone rubber sheets 1102 and a plurality of coloredsilicone rubber sheets 1103 arranged in alternating fashion in thedirection parallel to the surface of the anti-glare layer 1101. Theadjoining surfaces of the transparent silicone rubber sheets 1102 andthe colored silicone rubber sheets 1103 are parallel to each other. Thewidth, specifically, the thickness in the lateral direction of FIG. 22of the transparent silicone rubber sheets 1102 and colored siliconerubber sheets 1103, is selected with consideration for the fact that thetransparency and parallel light transmittance are determined by theratio of the width of the transparent silicone rubber sheets 1102 to thewidth of the colored silicone rubber sheets 1103, and for the fact thatthe range of viewing angles is determined by the refractive index andwidth of the transparent silicone rubber sheets 1102 and the overallthickness of the anti-eavesdropping device. In Prior Art 1, the width ofthe transparent silicone rubber sheets 1102 is described as being 100 to200 μm, for example, and preferably 120 to 150 μm; and the width of thecolored silicone rubber sheets 1103 is described as being 10 to 50 μm,for example, and preferably 10 to 30 μm. According to Prior Art 1, bysetting such values for the widths of the transparent silicone rubbersheets 1102 and colored silicone rubber sheets 1103, the anti-glarelayer 1101 can be endowed with a parallel ray transmittance ofapproximately 80% or higher with a maximum of 85% or higher, and avisibility range of 90 to 120 degrees. According to Prior Art 1, thethickness of the anti-eavesdropping device is set to about 0.15 to 0.5mm with consideration for the angle range of visibility, translucency,and handling, and is more preferably set to about 0.15 to 0.3 mm toenable attachment to the liquid crystal display of a small, thin mobiletelephone or the like.

Affixing this type of anti-eavesdropping device to the display surfaceof a display device prevents light from exiting from theanti-eavesdropping device since light that is incident in a directiontilted with respect to the anti-eavesdropping device is absorbed by thecolored silicone rubbers sheets forming a louver. Specifically, theanti-glare layer 1101 of the anti-eavesdropping device used for aninformation display demonstrates anti-eavesdropping effects. It isthereby impossible or extremely difficult for a third party presentbeside the user to see from the side or read the various types ofinformation displayed when the anti-eavesdropping device is mounted onthe liquid crystal display of the information display. Accordingly,since the information displayed on the information display is not leakedto a third party, the user of the information display can monitor andtransmit information comfortably without worrying about eavesdropping.

However, the anti-eavesdropping device described in Prior Art 1 has suchproblems as those described below. Specifically, when theanti-eavesdropping device described in Prior Art 1 is attached to thedisplay device, moiré occurs to a significant degree between the pixelsof the display device and the colored silicone rubber sheetsconstituting the anti-eavesdropping device, and the display quality isseverely reduced.

Techniques for suppressing moiré have been developed in the past toremedy this problem (see Japanese Patent No. 2622762, for example:hereinafter referred to as Prior Art 2). FIG. 23 is a diagram showing aconventional raster display device provided with a light control filmdisclosed in Prior Art 2; FIG. 24 is a top view showing the positioningof the light control film with respect to the display surface of thedisplay device; and FIG. 25 is a graph showing the relationship betweenangle β and pitch p, wherein the angle β (degrees) between the raster ofthe display device and the stripes of the light control film is plottedon the horizontal axis, and the pitch p (mm) of the moiré stripes isplotted on the vertical axis.

As shown in FIG. 23, the raster display device 3102 described in PriorArt 2 is installed in an in-vehicle information display system, forexample, and the in-vehicle information display system is composed of anautomobile state detection device 3101, a CRT (Cathode Ray Tube) displaydevice or other raster display device 3102 having a raster aligned sothat the pitch is a, an information display controller 3103, a lightcontrol film 3104 for controlling the transmission direction of light,and an operating input device 3106. The light control film 3104 isattached to the display surface of the raster display device 3102. Auser 3105 can see the raster display device 3102 through the lightcontrol film 3104.

The light control film 3104 controls the transmission direction ofincident light, and has light-transmitting and light-blocking portionsarranged in alternating stripes at a prescribed pitch therein. The lightcontrol film 3104 is reinforced by a glass plate. The light control film3104 is also offset with respect to the raster display device 3102 sothat the direction in which the stripes of the control film 3104 extendis tilted a prescribed angle β, for example, 10 degrees, with respect tothe raster direction of the raster display device.

As shown in FIG. 24, a moiré bar whose pitch is p occurs at theintersection between the raster (indicated by straight line A) and thestripe (indicated by straight line B) when the display device 3102 andthe light control film 3104 are viewed from the front. This moiré bar isindicated by the dotted line C. In this case, when the angle β isrelatively small, the pitch p of the moiré bar can be computed using theEq. 1 below, where a is the pitch of the raster, k is a coefficient,(a×k) is the pitch of the stripes, and B (degrees) is the angle formedby the extension direction of the raster and the extension direction ofthe stripes. $\begin{matrix}{p = \frac{\frac{a \times k}{\cos\quad\beta}}{\sqrt{\left( {\tan\quad\beta} \right)^{2} + \left( {1 - \frac{k}{\cos\quad\beta}} \right)^{2}}}} & \left\lbrack {{Eq}.\quad 1} \right\rbrack\end{matrix}$

FIG. 25 is a diagram in which the abovementioned Eq. 1 is plotted. Asshown in FIG. 25, the pitch p of the moiré bar decreases as the angle βincreases, regardless of the size of the coefficient k. By making thepitch p of the moiré bar about the same or smaller than the pitch a ofthe raster, the moiré bar can be made less visible to the user. Theangle β required to achieve this result is approximately 3 degrees orlarger.

According to the description in Prior Art 2, a moiré bar is thusgenerated by the superposition of the light-blocking portions of thecontrol film and the arrangement of the pixels in the image displaydevice when a control film in which light-transmitting striped portionsand light-blocking striped portions are arranged in alternating fashionand which is used to control the transmission direction of light ismounted for the purpose of preventing eavesdropping and the like on thedisplay surface of an image display device in which a plurality ofpixels are periodically arranged in two dimensions, and in which anarbitrary image is displayed. However, by tilting the extensiondirection of the control film stripes three degrees or more with respectto the arrangement direction of the pixels of the image display device,the pitch of the moiré bar can be made smaller than the arrangementpitch of the pixels, and the effect of moiré on the image can be reducedto a certain degree.

However, the above-described conventional technique has such problems asthose described below. As described in Prior Art 2, moiré can be reducedto a certain degree by tilting the extension direction of the controlfilm stripes with respect to the arrangement direction of the pixels ofthe image display device. However, moiré still occurs, and themoiré-reducing effects are inadequate. As described also in FIG. 3 ofPrior Art 2, the period of the moiré increases particularly when thepitch of the opaque portions of the control film is near the pixel pitchof the display device. It is therefore impossible to adequately reducemoiré even when the control film is placed in a tilted position. In thiscase, when the tilt angle of the control film is increased in order toreduce moiré, the direction in which the light is restricted,specifically, the direction in which eavesdropping is prevented, istilted from the horizontal direction, thus creating discomfort for theuser.

SUMMARY OF THE INVENTION

An object of the present invention is to provide a display devicecapable of reducing moiré in a display device having increased displaydirectivity, to provide a terminal device that uses the display device,and to provide a light source device and optical member that areincorporated into the display device.

The display device according to the present invention has a displaypanel in which a plurality of pixels are arranged in a matrix; alight-direction restricting element which is interposed in the path ofthe light incident on the display panel or the light exiting from thedisplay panel, and which is provided with a plurality of transparentareas and a plurality of light-absorbing areas arranged in alternatingfashion in a first direction that differs from the arrangement directionof the pixels; and anisotropic scattering unit for scattering incidentlight to a greater degree in the arrangement direction of moiré createdbetween the display panel and the light-direction restricting elementthan in the first direction.

In the present invention, the light-direction restricting elementrestricts the direction of light in a first direction, and theanisotropic scattering unit scatters light to a greater degree in thearrangement direction of the moiré than in the first direction, wherebymoiré can be obscured without compromising the light-directionrestricting effects of the light-direction restricting element.

In this instance, the direction of maximum scattering by the anisotropicscattering unit is preferably one direction among the arrangementdirections of the pixels. Discomfort during use can thereby be reducedsince the scattering effects can be set perpendicular with respect tothe side of the display device constituting the display surface.

Alternatively, the direction of maximum scattering by the anisotropicscattering unit is preferably the direction orthogonal to the firstdirection. It is thereby possible to more effectively prevent thelight-direction restricting effects of the light-direction restrictingelement from being compromised.

The display panel, the light-direction restricting element, and theanisotropic scattering unit may also be arranged in sequence along thelight path. A louver is thereby provided on the user side of the displaypanel, and the anisotropic scattering structure is formed in the louver.The user can therefore easily attach and detach a louver equipped withan anisotropic scattering structure according to the situation.

The display panel, the anisotropic scattering unit, and thelight-direction restricting element may also be arranged in sequencealong the light path. The anisotropic scattering unit can thereby bemade to function as an anisotropic scattering adhesion layer, there isno need to provide a textured structure or other anisotropic scatteringunit to the surface of the light-direction restricting element, and costcan be reduced.

Alternatively, the light-direction restricting element, the anisotropicscattering unit, and the display panel may be arranged in sequence alongthe light path. The display panel can thereby be disposed as far aspossible towards the user. It is therefore possible to reduce thediscomfort caused by a display that appears to be recessed into thedevice with respect to the outermost surface of the display device by anamount commensurate with the thickness of the member provided to thefront surface of the display panel.

Furthermore, the anisotropic scattering unit may comprise a transparentsubstrate and a convex portion which extends in one direction and isformed on the surface of the transparent substrate. In this instance,the anisotropic scattering unit may be a one-dimensionally arrangedprism sheet in which a plurality of prisms extending in one directionare arranged parallel to each other, or a lenticular lens in which aplurality of cylindrical lenses extending in one direction are arrangedparallel to each other. The anisotropic scattering unit may alsocomprise a transparent substrate and a concave portion that extends inone direction and is formed on the surface of this transparentsubstrate.

Alternatively, the anisotropic scattering unit may be a convex portionformed on the surface of the light-direction restricting element or thesurface of the display panel. In this instance, the anisotropicscattering unit may be a one-dimensionally arranged prism structure inwhich a plurality of prisms extending in one direction are arrangedparallel to each other, or a lenticular lens structure in which aplurality of cylindrical lenses extending in one direction are arrangedparallel to each other. The scattering anisotropy of the anisotropicscattering unit can thereby be enhanced. The anisotropic scattering unitmay also be a concave portion formed on the surface of thelight-direction restricting element or the surface of the display panel.The transparent substrate is thereby made unnecessary, and the thicknessof the display device can therefore be reduced. The anisotropicscattering unit and the light-direction restricting element ortransmissive liquid crystal panel are also optically bonded to eachother. Therefore, interference fringes can be prevented from occurring,and the quality of the display can be even further enhanced.

Alternatively, the anisotropic scattering unit may be an anisotropicscattering adhesion layer for affixing the light-direction restrictingelement to the display panel. The anisotropic scattering unit may alsobe disposed inside the display panel. In this instance, the displaypanel may have an optical film, and the anisotropic scattering unit maybe an anisotropic scattering adhesion layer for fixing the optical filmto the substrate of the display panel. There is thereby no need toprovide anisotropic scattering unit to the surface of thelight-direction restricting element and the like, and cost can bereduced.

The display device according to the present invention may furthermorecomprise a transparent/scattering state switching element which iscapable of switching between a state for transmitting incident light anda state for scattering the light, and which is interposed in the path ofthe light that is incident on the display panel. The visible range ofthe display can thereby be changed by switching thetransparent/scattering state switching element between the transparentstate and the scattering state. In this instance, moiré can be reducedparticularly in the transparent state, and excellent display quality canbe achieved.

The anisotropic scattering unit in this instance is preferably ananisotropic scattering adhesion layer for affixing thetransparent/scattering state switching element to the light-directionrestricting element. There is thereby no need to provide an anisotropicscattering element, and thin profile and low cost can be achieved.

The display panel may also be a liquid crystal panel. The liquid crystaldisplay panel in this instance is preferably a liquid crystal displaypanel that operates on a lateral field principle, a multi-domainvertical alignment principle, or a film-compensated TN principle.Contrast inversion of the display can thereby be minimized, andvisibility can be enhanced when the transparent/scattering stateswitching element is in the scattering state.

Another display device according to the present invention has alight-direction restricting element provided with a plurality oftransparent areas and a plurality of light-absorbing areas arranged inalternating fashion in a first direction; a transparent/scattering stateswitching element capable of switching between a state for transmittingthe light incident from the light-direction restricting element and astate for scattering the light; and a display panel which displays animage by transmitting the light incident from the transparent/scatteringstate switching element, and in which a plurality of pixels are arrangedin a matrix in a direction that differs from the first direction;wherein the transparent/scattering state switching element scattersincident light to a greater degree in the arrangement direction of moirécreated between the display panel and the light-direction restrictingelement than in the first direction when in the light-transmittingstate.

The terminal device according to the present invention has theaforementioned display device.

The direction of maximum scattering of light by the anisotropicscattering unit or the transparent/scattering state switching element ispreferably the direction perpendicular to the screen of the terminaldevice. Eavesdropping from the lateral direction can thereby beeffectively prevented when the terminal device is in use.

The terminal device according to the present invention may be a mobiletelephone, a personal information terminal, a gaming device, a digitalcamera, a video camera, a video player, a notebook-type personalcomputer, a cash dispenser, or a vending machine.

The light source device according to the present invention has a planarlight source for emitting light in a plane; a light-directionrestricting element which is interposed in the path of the light andwhich is provided with a plurality of transparent areas and a pluralityof light-absorbing areas arranged in alternating fashion in a firstdirection; and anisotropic scattering unit for scattering incident lightto a greater degree in a direction other than the first direction.

This light source device can be built into a display panel and suitablyused as a light source device for a display device that preventseavesdropping and has reduced moiré.

Another light source device according to the present invention has aplanar light source of emitting light in a plane; a light-directionrestricting element which is interposed in the path of the light andwhich is provided with a plurality of transparent areas and a pluralityof light-absorbing areas arranged in alternating fashion in a firstdirection; and a transparent/scattering state switching element capableof switching between a state for transmitting the light incident fromthe light-direction restricting element and a state for scattering thelight; wherein the transparent/scattering state switching elementscatters incident light to a greater degree in a direction other thanthe first direction when in the light-transmitting state.

The optical member according to the present invention has alight-direction restricting element provided with a plurality oftransparent areas and a plurality of light-absorbing areas arranged inalternating fashion in a first direction; and anisotropic scatteringunit which scatters incident light to a greater degree in a directionother than the first direction and which is integrally formed in thesurface of the light-direction restricting element.

In the present invention, an optical member is obtained that is capableof reducing moiré when used in combination with a display panel.

Another optical member according to the present invention has alight-direction restricting element which is provided with a pluralityof transparent areas and a plurality of light-absorbing areas arrangedin alternating fashion in a first direction, and which scatters incidentlight to a greater degree in a direction other than the first directionwhen in the light-transmitting state.

According to the present invention, moiré can be reduced in a displaydevice in which the directivity of the display is increased.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view showing the display device according to afirst embodiment of the present invention;

FIG. 2 is a top view showing a louver as the light-direction restrictingelement of the display device shown in FIG. 1;

FIG. 3 is a top view showing the anisotropic scattering sheet of thedisplay device shown in FIG. 1;

FIG. 4 is a top view showing the relationship between thelight-restricting direction of the louver and the scattering directionof an anisotropic diffusion sheet;

FIG. 5 is a perspective view showing the terminal device according tothe present embodiment;

FIG. 6 is a top view showing the relationship between thelight-restricting direction of the louver and the pixel arrangementdirection of the transmissive liquid crystal panel in the presentembodiment;

FIG. 7 is a graph in which the abovementioned Eq. 3 is plotted for angleα, wherein the angle α is plotted on the horizontal axis and the angle βis plotted on the vertical axis;

FIG. 8 is a perspective view showing the display device according to asecond embodiment of the present invention;

FIG. 9 is a top view showing the anisotropic scattering structure formedon the surface of the louver;

FIG. 10 is a top view showing the positional relationship between thelouver and the anisotropic scattering structure;

FIG. 11 is a top view showing the relationship between thelight-restricting direction of the louver and the pixel arrangementdirection of the transmissive liquid crystal panel in the presentembodiment;

FIG. 12 is a perspective view showing the display device according to athird embodiment of the present invention;

FIG. 13 is a top view showing the anisotropic scattering structure ofthe display device shown in FIG. 12;

FIG. 14 is a top view showing the relationship between thelight-restricting direction of the louver and the scattering directionof the anisotropic scattering structure in the display device shown inFIG. 12;

FIG. 15 is a perspective view showing the display device according to afourth embodiment of the present invention;

FIG. 16 is a perspective view showing the anisotropic scattering sheetof the display device shown in FIG. 15;

FIG. 17 is a perspective view showing the anisotropic scattering sheetin a modification of the fourth embodiment;

FIG. 18 is a sectional view showing the display device according to afifth embodiment of the present invention;

FIG. 19 is a sectional view showing the transparent/scattering stateswitching element in the display device shown in FIG. 18;

FIG. 20 is a sectional view showing the display device according to asixth embodiment of the present invention;

FIG. 21 is a graph showing the voltage dependency of the haze of thePNLC layer in the X-axis direction and Y-axis direction, wherein thevoltage applied to the PNLC layer is plotted on the horizontal axis, andthe haze of the PNLC layer is plotted on the vertical axis;

FIG. 22 is a sectional view showing the conventional anti-eavesdroppingdevice described in Prior Art 1;

FIG. 23 is a diagram showing the raster display device provided with theconventional light control film described in Prior Art 2;

FIG. 24 is a top view showing the positioning of the light control filmwith respect to the display surface of the display device; and

FIG. 25 is a graph showing the relationship between angle β and pitch P,wherein the angle β formed by the raster and the stripes of the lightcontrol film of the display device is plotted on the horizontal axis,and the pitch p of the moiré bar is plotted on the vertical axis.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The display device, terminal device, light source device, and opticalmember according to embodiments of the present invention will bedescribed in detail hereinafter with reference to the accompanyingdrawings. The display device, terminal device, light source device, andoptical member according to a first embodiment of the present inventionwill first be described. FIG. 1 is a perspective view showing thedisplay device according to the present embodiment; FIG. 2 is a top viewshowing a louver as the light-direction restricting element of thedisplay device shown in FIG. 1; FIG. 3 is a top view showing theanisotropic scattering sheet of the display device shown in FIG. 1; FIG.4 is a top view showing the relationship between the light-restrictingdirection of the louver and the scattering direction of an anisotropicdiffusion sheet; and FIG. 5 is a perspective view showing the terminaldevice according to the present embodiment.

As shown in FIG. 1, a light source device 1 is provided in the displaydevice 2 according to the first embodiment, and a transmissive liquidcrystal panel 7 is provided on the light source device 1. The lightsource device 1 is provided with an optical waveguide 3; a light source51 provided on the side surface of the optical waveguide 3; a louver 112as a light-direction restricting element disposed on the front surfaceside, specifically, the user side of the optical waveguide 3; and ananisotropic scattering sheet 61 as an anisotropic scattering elementdisposed on the front surface side, specifically, the user side, of thelouver 112. Specifically, an optical waveguide 3, a louver 112, ananisotropic scattering sheet 61, and a transmissive liquid crystal panel7 are layered in sequence towards the user in the display device 2.

An XYZ orthogonal coordinate system is set up as described below forconvenience in the present specification. The direction from the lightsource 51 to the optical waveguide 3 is the +X direction, and theopposite direction is the −X direction. The +X direction and the −Xdirection are collectively referred to as the X-axis direction. Withinthe direction parallel to the light-exiting surface 43 of the opticalwaveguide 3, the direction orthogonal to the X-axis direction is theY-axis direction. Furthermore, the direction that is orthogonal to boththe X-axis direction and the Y-axis direction is the Z-axis direction;and within the Z-axis direction, the direction from the opticalwaveguide 3 to the louver 112 is the +Z direction, and the oppositedirection is the −Z direction. The +Z direction is the frontaldirection, specifically, the direction towards the viewer. The +Ydirection is the direction in which a right-handed coordinate system isestablished. Specifically, when the person's right thumb is in the +Xdirection, and the index finger is in the +Y direction, the middlefinger is in the +Z direction.

The light source 51 is a point light source that emits light in the +Xdirection. In an example of the light source, four LEDs (Light-EmittingDiode), for example, are provided along the Y-axis direction. Theoptical waveguide 3 is a plate-shaped member composed of glass oranother transparent material, for example, and the principal surfacethereof is perpendicular to the Z-axis direction and arranged so thatthe light emitted from the light source 51 is incident on the surfacethat faces in the −X direction. The optical waveguide 3 emits lightsubstantially uniformly in a plane from the light-exiting surface 43,specifically, from the principal surface facing in the +Z direction,while reflecting the light incident from the surface on the side of the−X direction between the principal surfaces, and propagating the lightin the +X direction.

In the louver 112 as shown in FIG. 2, light-transmitting transparentareas 112 a for transmitting light and absorbent areas 112 b forabsorbing light, for example, are formed and arranged in alternatingfashion in the direction parallel to the surface of the louver 112. Thetransparent areas 112 a and absorbent areas 112 b are belt-shaped areasextending parallel to each other as viewed from the directionperpendicular to the surface of the louver 112, specifically, from theZ-axis direction, and the extension direction thereof is tilted at anangle α towards the −Y direction from the +X direction. Specifically,the direction in which the transparent areas 112 a and the absorbentareas 112 b are arranged in alternating fashion is tilted at an angle αtowards the +X direction from the +Y direction. The angle α is set to 20degrees, for example. The pitch at which the absorbent areas 112 b arearranged is set to 140 μm, for example.

As shown in FIG. 3, anisotropic scattering structures 611 are formed onthe surface of the anisotropic scattering sheet 61 facing in the +Zdirection. The anisotropic scattering structures 611 are belt-shapedconvex portions extending in the Y-axis direction, and a pluralitythereof are formed on the surface of the anisotropic scattering sheet61. Numerous anisotropic scattering structures 611 are therebytransected by a line traced in the X-axis direction on the surface ofthe anisotropic scattering sheet 61 that faces the +Z direction. Thissurface therefore has a great deal of irregularity in the X-axisdirection. In contrast, a line traced in the Y-axis direction along thissurface crosses few or no anisotropic scattering structures 611. Thissurface therefore has little irregularity in the Y-axis direction.

In more general terms, the surface of the anisotropic scattering sheet61 has numerous irregularities in a specific direction, and has fewirregularities in the direction orthogonal to this specific direction.In the present embodiment, the aforementioned specific direction inwhich there are more irregularities is set to the X-axis direction.

Therefore, the direction in which the transparent areas 112 a andabsorbent areas 112 b of the louver 112 are arranged in alternatingfashion is tilted 20 degrees with respect to the longitudinal direction(Y-axis direction) of the anisotropic scattering structures 611 of theanisotropic scattering sheet 61, as shown in FIG. 4.

The transmissive liquid crystal panel 7 displays information using thelight emitted by the light source device 1 disposed behind the liquidcrystal panel as viewed from the user side, and numerous pixels 71 (seeFIG. 6) having transparent display areas are arranged therein in amatrix in the X-axis direction and the Y-axis direction shown in FIG. 1.The arrangement pitch of the pixels 71 is 150 μm, for example.

As shown in FIG. 5, the terminal device according to the presentembodiment is a mobile telephone 9. The aforementioned display device 2is installed in this mobile telephone 9. The X-axis direction of thedisplay device 2 corresponds to the longitudinal direction of the screenof the mobile telephone 9, and the Y-axis direction corresponds to thetransverse direction of the screen of the mobile telephone 9.

The operation of the display device according to the present embodimentthus configured will next be described. As shown in FIG. 1, the lightsource 51 emits light in the +X direction. This light enters the opticalwaveguide 3 from the side facing the −X direction, and is propagatedthrough the optical waveguide 3 while being totally reflected by thesurface thereof. A portion of the light at this time is emitted from thelight-exiting surface 43 of the optical waveguide 3. As a result, lightis emitted with substantial uniformity in a plane from the entirelight-exiting surface 43 of the optical waveguide 3.

The light emitted from the optical waveguide 3 enters the louver 112.Among the light entering the louver 112, the light that is incident onthe absorbent areas 112 b (see FIG. 2) is absorbed and blocked by theabsorbent areas 112 b. The light that is propagated through only thetransparent areas 112 a without entering the absorbent areas 112 b isemitted from the louver 112. Accordingly, among the light rays incidenton the louver 112, the light rays that are tilted from the +Z directionat an angle equal to or greater than a specific angle in the direction(hereinafter referred to as the light regulating direction) in which thetransparent areas 112 a and absorbent areas 112 b are alternatelyarranged are always incident on the absorbent areas 112 b, and do notpass through the louver 112. As a result, in the light-restrictingdirection, the angle of tilt from the +Z direction of the direction ofthe light emitted from the louver 112 is kept within a range of anglesthat are smaller than a specific angle. Specifically, the directivity isincreased. In contrast, since this type of restriction does not operatefor the direction orthogonal to the light-restricting direction, thedirectivity in this direction is not increased.

The light emitted from the louver 112 is incident on the anisotropicscattering sheet 61. As previously mentioned, belt-shaped anisotropicscattering structures 611 (see FIG. 3) extending in the Y-axis directionare formed in the anisotropic scattering sheet 61, and the density ofirregularities in the surface of the anisotropic scattering sheet 61 ishigh in the X-axis direction and low in the Y-axis direction. The lightthat is incident on the anisotropic scattering sheet 61 is thereforescattered by the anisotropic scattering structures 611, but thescattering has high anisotropy in the X-axis direction and lowanisotropy in the Y-axis direction.

The light that is scattered mainly in the X-axis direction and emittedfrom the anisotropic scattering sheet 61 is incident on the transmissiveliquid crystal panel 7. The light passes through the transmissive liquidcrystal panel 7, whereby the image displayed by the transmissive liquidcrystal panel 7 is associated with the light, and the light is emittedfrom the display device 2. An image can thereby be displayed.

Following is a more-detailed description of the operation by which theanisotropic scattering sheet 61 prevents the occurrence of the moiréthat commonly tends to occur between the louver 112 and the transmissiveliquid crystal panel 7. FIG. 6 is a top view showing the relationshipbetween the light-restricting direction of the louver and the pixelarrangement direction of the transmissive liquid crystal panel. Aspreviously mentioned, the extension direction of the transparent areas112 a and absorbent areas 112 b in the louver 112 is tilted from theX-axis direction at an angle α. Therefore, the arrangement direction(light-restricting direction) of the transparent areas 112 a andabsorbent areas 112 b is tilted from the Y-axis direction at an angle α.The angle α is 20 degrees, for example, and the arrangement pitch of theabsorbent areas is 140 μm, for example. As also previously mentioned,the pixels 71 of the display panel 7 are arranged in a matrix in theX-axis direction and Y-axis direction, and the arrangement pitch thereofis set to 150 μm.

As is shown in FIG. 6, if it is assumed that the corner on the (+X, −Y)side of a pixel 71 is point A and that the center line of an absorbentarea 112 b passes through this point A as viewed from the Z-axisdirection, then point B will be the point of intersection between theabsorbent area 112 b that faces the +Y direction and is adjacent to thisabsorbent area 112 b and the side of this pixel 71 that extends in theY-axis direction, point C will be the corner portion on the (+X, +Y)side of this pixel 71, and point D will be the foot of the perpendicularline drawn downward from point B onto the center line of the absorbentarea 112 b that includes point A. If the anisotropic scattering sheet 61were not provided, the straight line 8 linking point A and point B wouldbe the direction in which moiré extends. The hypotenuse AB of the righttriangle ABC is the same as the hypotenuse AB of the right triangle ABD,giving Eq. 2 below, where β is the angle formed by this moiré directionand the X-axis direction, Pv is the arrangement pitch of the absorbentareas 112 b of the louver 112, and Px is the arrangement pitch of thepixels 71. Furthermore, angle β is indicated by Eq. 3 below when Eq. 2is solved. FIG. 7 is a graph in which the abovementioned Eq. 3 isplotted for angle a, wherein the angle a is plotted on the horizontalaxis and the angle β is plotted on the vertical axis. In FIG. 7, thepitch Pv of the absorbent areas is 140 μm, and the pixel pitch Px is 150μm. $\begin{matrix}{\frac{Px}{\cos\left( {90^{\circ} - \beta} \right)} = \frac{Pv}{\sin\left( {\beta - \alpha} \right)}} & \left\lbrack {{Eq}.\quad 2} \right\rbrack \\{\beta = {{arc}\quad{\tan\left( \frac{{{Px} \times \sin}\quad\alpha}{{{{Px} \times \cos}\quad\alpha} - {Pv}} \right)}}} & \left\lbrack {{Eq}.\quad 3} \right\rbrack\end{matrix}$

When 20 degrees for angle a, 140 μm for the pitch Pv of the absorbentareas of the louver, and 150 μm for the pixel pitch Px are substitutedinto the abovementioned Eq. 3, the angle β between the moiré direction(extension direction of the straight line 8) and the X-axis direction iscomputed as 89 degrees. Specifically, the moiré direction issubstantially parallel to the Y-axis direction. Accordingly, if theanisotropic scattering sheet 61 were not provided, the user wouldrecognize moiré that is arranged substantially in the X-axis directionand extends substantially in the Y-axis direction. Specifically, in themobile telephone 9 (see FIG. 5) it would be possible to observe moiréthat extends in the substantially horizontal direction of the screen andis arranged in the substantially perpendicular direction.

Moiré that occurs between the louver 112 and the display panel 7 thusextends substantially in the Y-axis direction, and is arranged in thesubstantially X-axis direction. On the other hand, the anisotropicscattering sheet 61 is capable of scattering light mainly in the X-axisdirection. Specifically, the direction of maximum scattering of light bythe anisotropic scattering sheet 61 is perpendicular to the screen ofthe mobile telephone 9. As a result, light can be scattered in thearrangement direction of the moiré, and the moiré can be obscured. Sincethe light-scattering effects are minimal in directions other than thearrangement direction of the moiré, there is little decrease in thedirectivity of the light restricted by the louver 112.

Since the light-restricting direction of the louver 112 is tilted 20degrees from the Y-axis direction in which the scattering effects of theanisotropic scattering sheet 61 are at minimum, the light-directionrestricting effects of the louver 112 are somewhat compromised. Sincethe light-restricting direction of the louver 112 is tilted 20 degreesfrom the Y-axis direction, specifically, from the horizontal directionof the screen of the mobile telephone 9, the light-restricting effectsof the louver 112 become asymmetrical to the left and right. However,the anisotropic scattering effects are symmetrical with respect to theX-axis direction, and are therefore symmetrical to the left and right inthe screen of the mobile telephone 9. Therefore, the left-rightasymmetry of the light-restricting effects of the louver 112 can besupplemented to a certain degree, and the discomfort caused by thetilted placement of the louver can be reduced.

As is apparent from FIG. 6, the arrangement direction of the moirécoincides with the Y-axis direction when the angle α is 0 degrees. Inthis case, the light must also be scattered in the Y-axis direction inorder for the moiré to be obscured by the anisotropic scattering sheet61, and the light-restricting effects of the louver 112 are cancelledout. However, as shown in FIG. 7, when the angle α is an angle otherthan 0 degrees, specifically, when the light-restricting direction ofthe louver 112 is tilted with respect to the arrangement direction ofthe pixels in the transmissive liquid crystal panel 7, the angle β isdifferent from 0 degrees, and the arrangement direction of the moiré istilted with respect to the light-restricting direction. Therefore, byproviding the anisotropic scattering sheet 61 and scattering the lightanisotropically, moiré can be obscured while the light-restrictingeffects are maintained. The angle α is preferably made as small aspossible, and the light-restricting direction of the louver 112 ispreferably caused to approach the Y-axis direction in order toeffectively obtain anti-eavesdropping effects in the mobile telephone 9.However, as shown in FIG. 7, the angle β most closely approaches 90degrees when the angle α is approximately 20 degrees, and thearrangement direction of the moiré approaches the X-axis direction. Theangle α is therefore preferably greater than 0 degrees and less than orequal to 20 degrees, and is preferably 20 degrees, for example.

The effects of the present embodiment will next be described. Aspreviously mentioned, moiré occurs between the louver 112 and the liquidcrystal panel 7 if the anisotropic scattering sheet 61 is not provided.In contrast, by tilting the light-restricting direction of the louver112 away from the pixel arrangement direction of the liquid crystalpanel 7 in the present embodiment, the arrangement direction of themoiré can be made different from the light-restricting direction of thelouver 112. Moreover, by providing the anisotropic scattering sheet 61,the anisotropic scattering structures 611 formed along the Y-axisdirection can be caused to scatter incident light anisotropically, andto scatter the light to a large extent in the arrangement direction ofthe moiré, and only to a small degree in the light-restrictingdirection. Moiré can thereby be reduced without significantlycompromising the light-restricting effects of the louver 112. As aresult, the directivity of light in the frontal direction can beincreased, and excellent display quality can be achieved withoutsignificantly compromising the anti-eavesdropping effects.

The pitch of the absorbent areas of the louver, the light-restrictingdirection, the pixel pitch of the liquid crystal panel, and theextension direction of the anisotropic scattering structures of theanisotropic scattering sheet in the present embodiment are not limitedto the abovementioned values, and may be appropriately modified inranges that have the same effects, as described above. Specifically,even when the pitch Pv of the absorbent areas and the pixel pitch Px ofthe liquid crystal panel are set to values other than those describedabove, the same effects as those of the present embodiment are obtainedif the value of angle α at which angle β is approximately 90 degrees iscomputed based on the abovementioned Eq. 3.

An example was described in the present embodiment in which thecomponents are arranged in the sequence “transmissive liquid crystalpanel”→“anisotropic scattering sheet”→“louver” as viewed in the +Zdirection, that is, from the user side. However, the present inventionis not necessarily limited by this sequence, and the appropriatesequence of arrangement of the components may be changed insofar as thesame effects are obtained. Examples of such arrangements besides theabovementioned sequence include the sequence “anisotropic scatteringsheet”→“transmissive liquid crystal panel”→“louver”; the sequence“anisotropic scattering sheet”→“louver”→“transmissive liquid crystalpanel”; the sequence “louver”→“anisotropic scatteringsheet”→“transmissive liquid crystal panel”; and other sequences. In thiscase, however, it is possible to further reduce the discomfort caused bya display that appears to be recessed into the device with respect tothe outermost surface of the display device by an amount commensuratewith the thickness of the member provided to the front surface of thedisplay panel when the transmissive liquid crystal panel is disposed asclose to the user side as possible.

Furthermore, an example was described in the present embodiment in whichthe anisotropic scattering structures 611 are convex portions formed onthe surface facing the +Z direction of the anisotropic scattering sheet61. However, the anisotropic scattering structures 611 may be formed onthe surface facing the −Z direction of the anisotropic scattering sheet61, and may be concave rather than convex. Any anisotropic scatteringsheet may be used insofar as it scatters light in anisotropic fashion.For example, a template may be prepared in which an anisotropicscattering pattern is machined, and a film may be used on which thepattern of the template is transferred by a hot embossing method or a 2Pmethod; a holographic diffuser may be used in which a one-dimensionalhologram pattern is formed; or a common isotropic scattering sheet maybe used that is stretched to create anisotropic properties.

An example was described in the present embodiment in which atransmissive liquid crystal panel is used as the display panel. However,the present invention is not limited to this configuration, and anypanel that has a transmissive area in each pixel may be used. Atransflective liquid crystal panel having a reflective area in a portionof each pixel, a visible-everywhere transflective liquid crystal panel,or a micro-reflective liquid crystal panel may also be used. The displaypanel is also not limited to a liquid crystal panel, and any displaypanel that uses a light source device may be used.

The terminal device was also described as being a mobile telephone inthe present embodiment, but the present invention is not limited by thisconfiguration, and may be applied to PDAs, personal TVs, gaming devices,digital cameras, digital video cameras, notebook-type personalcomputers, and various other types of mobile terminal devices. Thedisplay device may be installed not only in mobile terminal devices, butin cash dispensers, vending machines, monitors, television receivers,and other various types of fixed-mount terminal devices.

A second embodiment of the present invention will next be described.FIG. 8 is a perspective view showing the display device according to thepresent embodiment; FIG. 9 is a top view showing the anisotropicscattering structure formed on the surface of the louver; and FIG. 10 isa top view showing the positional relationship between the louver andthe anisotropic scattering structure. In the aforementioned firstembodiment, the louver and the anisotropic scattering unit are disposedbetween the light source device and the transmissive liquid crystalpanel. In contrast, the louver and anisotropic scattering unit areintegrally formed and disposed on the user side of the transmissiveliquid crystal panel in the second embodiment. The surface on the sideof the transmissive liquid crystal panel on which the anisotropicscattering unit is not formed in the louver is shaped into a smoothadhesion surface with a mirror finish, and is optically bonded to thetransmissive liquid crystal panel. Furthermore, the longitudinaldirection of the anisotropic scattering unit is tilted with respect tothe arrangement direction of the pixels. The pitch of the absorbentareas of the louver is also set to 160 μm.

Specifically, in the display device 21 according to the presentembodiment as shown in FIG. 8, a light source device 11 is provided, andthis light source device 11 has an optical waveguide 3 and a lightsource 51 provided to the side of the optical waveguide 3. Atransmissive liquid crystal panel 7 is also provided on the user side,specifically, on the side of the +Z direction, of the light sourcedevice 11. The structure of the light source 51, optical waveguide 3,and transmissive liquid crystal panel 7 is the same as in theaforementioned first embodiment. Furthermore, a louver 212 as alight-direction restricting element is provided facing the +Z directionof this transmissive liquid crystal panel 7. The louver 212 is opticallybonded to the transmissive liquid crystal panel 7, for example.Anisotropic scattering structures 621 are formed directly on the surfaceof the louver 212 facing the +Z direction.

As shown in FIG. 9, the anisotropic scattering structures 621 arebelt-shaped convex portions extending in a direction that is tilted atan angle α towards the +X direction with respect to the +Y direction.Therefore, the arrangement direction thereof is tilted at an angle αtowards the −Y direction with respect to the +X direction. The surfaceof the louver 212 facing the +Z direction is thereby provided withnumerous irregularities in a specific direction (arrangement direction)that is tilted at an angle α in the −Y direction with respect to the +Xdirection, and has few irregularities in the direction (longitudinaldirection of the anisotropic scattering structures 621) orthogonal tothis specific direction.

Aspects of the configuration other than the anisotropic scatteringstructures 621 in the louver 212 are the same as in the louver 112 ofthe aforementioned first embodiment. Specifically, in the louver 212 asshown in FIG. 10, transparent areas 212 a and absorbent areas 212 b arearranged in alternating fashion, and the arrangement direction thereof,specifically, the light-restricting direction thereof, is tilted at anangle α towards the −Y direction with respect to the +X direction. Thelight-restricting direction of the louver 212 and the longitudinaldirection of the anisotropic scattering structures 621 are thereforeparallel to each other. The angle α is set to 20 degrees, for example.Other aspects of the configuration of the present embodiment are thesame as in the aforementioned first embodiment.

The operation of the display device of the present embodiment thusconfigured will next be described. As shown in FIG. 8, when the lightsource 51 emits light, the light is incident on the optical waveguide 3,and is emitted in a plane from the light-exiting surface 43 of theoptical waveguide 3. The light passes through the transmissive liquidcrystal panel 7, whereby an image is associated with the light. Thelight emitted from the transmissive liquid crystal panel 7 then entersthe louver 212, the direction of the light is restricted, and thedirectivity of the light is increased. These operations are the same asin the aforementioned first embodiment. This light is anisotropicallyscattered by the anisotropic scattering structures 621 formed on the +Zdirection side of the louver 212, and is emitted from the display device21.

The operation by which moiré is eliminated by the anisotropic scatteringstructures 621 will be described in further detail hereinafter. FIG. 11is a top view showing the relationship between the light-restrictingdirection of the louver 212 and the pixel arrangement direction of thetransmissive liquid crystal panel 7. As previously mentioned, thetransparent areas 212 a for transmitting light and the absorbent areas212 b for absorbing light are arranged in alternating fashion in adirection that is tilted at an angle α towards the −Y direction from the+X direction. The angle α is 20 degrees, for example, and the pitch ofthe absorbent areas is set to 160 μm, for example. As also previouslymentioned, numerous pixels 71 are arranged in a matrix in the X-axisdirection and Y-axis direction, and the arrangement pitch thereof is setto 150 μm. Specifically, the pitch of the absorbent areas of the louveris larger than the pixel pitch in the present embodiment.

As shown in FIG. 6, since the pitch of the absorbent areas of the louveris smaller than the pixel pitch in the aforementioned first embodiment,the direction in which the moiré is tilted with respect to the X-axisdirection is the same as the direction in which the absorbent areas ofthe louver are tilted with respect to the X-axis direction. In contrast,in the present embodiment as shown in FIG. 11, the moiré direction istilted with respect to the X-axis direction to the opposite side fromthe direction in which the absorbent areas of the louver are tilted withrespect to the X-axis direction.

If it is assumed that the corner on the (+X, +Y) side of a pixel 71 ispoint B and that the center line of one absorbent area 212 b passesthrough this point B as viewed from the Z-axis direction, then point Awill be the point of intersection between the absorbent area 212 b thatfaces the −Y direction and is adjacent to this absorbent area 212 b andthe side of this pixel 71 that extends in the Y-axis direction, point Cwill be the corner portion on the (+X, −Y) side of this pixel 71, andpoint D will be the foot of the perpendicular line drawn downward frompoint B onto the center line of the absorbent area 212 b that includespoint A. If the anisotropic scattering sheet 61 were not provided, thestraight line 8 linking point A and point B would be the direction inwhich moiré extends. The hypotenuse AB of the right triangle ABC is thesame as the hypotenuse AB of the right triangle ABD, giving Eq. 4, whereβ is the angle formed by this moiré direction and the X-axis direction,Pv is the arrangement pitch of the absorbent areas 212 b of the louver212, and Px is the arrangement pitch of the pixels 71. Furthermore,angle β is indicated by Eq. 5 below when Eq. 4 is solved.$\begin{matrix}{\frac{Pv}{\cos\left( {90^{\circ} - \beta - \alpha} \right)} = \frac{Px}{\cos\left( {90 - \beta} \right)}} & \left\lbrack {{Eq}.\quad 4} \right\rbrack \\{\beta = {{arc}\quad{\tan\left( \frac{{{Px} \times \sin}\quad\alpha}{{Pv} - {{{Px} \times \cos}\quad\alpha}} \right)}}} & \left\lbrack {{Eq}.\quad 5} \right\rbrack\end{matrix}$

When 20 degrees for angle a, 160 μm for the pitch Pv of the absorbentareas of the louver, and 150 μm for the pixel pitch Px are substitutedinto the abovementioned Eq. 5, the angle β of the moiré from the X-axisdirection is computed as 70 degrees. Specifically, the direction of themoiré is tilted at an angle of 70 degrees towards the +Y direction fromthe +X direction, as shown in FIG. 11. Since the angle α is 20 degrees,the extension direction of the absorbent areas 212 b is tilted 20degrees towards the −Y direction from the +X direction. The angle formedby the moiré direction and the extension direction of the absorbentareas therefore becomes 90 degrees. Since the arrangement direction ofthe moiré is orthogonal to the direction of the moiré, this direction istilted 20 degrees towards the −Y direction from the +X direction. Sincethe light-restricting direction of the louver 212 is also orthogonal tothe extension direction of the absorbent areas, this direction is tilted70 degrees towards the +Y direction from the +X direction. Thearrangement direction of the moiré is therefore orthogonal to thelight-restricting direction of the louver 212.

As previously mentioned, the direction in which the irregularity in theanisotropic scattering structures 621 is at maximum, specifically, thedirection of maximum scattering, is tilted at an angle α (20 degrees,for example) towards the −Y direction from the +X direction. Since thisdirection is the same as the arrangement direction of the moiré, themoiré-obscuring effects are maximized. The direction in which theirregularity in the anisotropic scattering structures 621 is at minimum,specifically, the direction of minimum scattering, is tilted at an angleβ (specifically, 70 degrees) towards the +Y direction from the +Xdirection. Since this direction is the same as the light-restrictingdirection of the louver 212, the effects that compromise thelight-restricting effects of the louver 212 are minimized. Moiré cantherefore be reduced with maximum efficiency while the adverse effectson the light-direction restricting effects of the louver are minimized.

The effects of the present embodiment will next be described. Asdescribed above, moiré can be reduced with maximum efficiency while theadverse effects on the light-direction restricting effects of the louverare minimized in the present embodiment. The display device can also bemade with a thin profile since the anisotropic scattering sheet isunnecessary. Furthermore, since the anisotropic scattering unit, thelouver, and the transmissive liquid crystal panel are optically bonded,interference fringes from air layers can be prevented from occurring,and an even better display quality can be achieved. The louver is alsoprovided on the user side of the display panel, and anisotropicscattering structures are formed in this louver. The user can thereforeeasily attach and detach a louver equipped with an anisotropicscattering structure according to the situation. Other effects in thepresent embodiment are the same as in the aforementioned firstembodiment.

A case was described above in which the angle α is 20 degrees, the pitchPv of the absorbent areas of the louver is 160 μm, and the pixel pitchPx is 150 μm, but the present embodiment is not limited by thisconfiguration. When arbitrary values are selected for the pitches Pv andPx, the same effects as in the abovementioned example can be obtained bysetting an angle α at which the value of (α+β) is 90 degrees based onthe abovementioned Eq. 5.

An example was also described in the present embodiment in whichanisotropic scattering structures are formed on the surface of thelouver facing the user, but the present invention is not limited to thisconfiguration. For example, the louver may be fixed to the transmissiveliquid crystal panel by an anisotropic scattering adhesion layer havinglong oriented fibers, and the anisotropic scattering layer may beembedded in the transmissive liquid crystal panel. As an example of thelatter configuration, anisotropic scattering structures may be formed onthe transmissive liquid crystal panel on the surface that faces thelight source device, and the polarizing plate of the transmissive liquidcrystal panel or another optical sheet may be fixed to the glasssubstrate of the transmissive liquid crystal panel by an anisotropicscattering adhesion layer. The same effects can be obtained by this typeof configuration as by the present embodiment. When the adhesion layeris endowed with anisotropic scattering effects, there is no need toprovide anisotropic scattering unit to the surface of thelight-direction restricting element, and cost can be reduced.

Furthermore, since the louver and anisotropic scattering structures aredisposed on the user side of the display panel in the presentembodiment, the display panel is not limited to a transmissive liquidcrystal panel, and a reflective liquid crystal panel may be used thatdoes not have a transparent area formed in each pixel. [The displaypanel] is also not limited to a liquid crystal panel, and aself-luminous display panel that does not use a backlight may be used.Examples of such self-luminous display panels include organicelectroluminescent display panels, plasma display panels, CRT displaypanels, LED display panels, field emission display panels, PALC (PlasmaAddress Liquid Crystal) display panels, and the like.

A third embodiment of the present invention will next be described. FIG.12 is a perspective view showing the display device according to thepresent embodiment; FIG. 13 is a top view showing the anisotropicscattering structure of the display device shown in FIG. 12; and FIG. 14is a top view showing the relationship between the light-restrictingdirection of the louver and the scattering direction of the anisotropicscattering structure in the display device shown in FIG. 12. The displaydevice according to the present embodiment differs from theaforementioned second display device in that the longitudinal directionof the anisotropic scattering structure is the Y-axis direction, thesame as in the first embodiment.

Specifically, in the same manner as in the second embodiment, theoptical waveguide 3, the transmissive liquid crystal panel 7, and thelouver 213 are provided in sequence in the +Z direction, specifically,in the direction towards the user, in the display device 22 according tothe present embodiment, as shown in FIG. 12. The light source 51 isprovided on the side of the optical waveguide 3. The light-restrictingdirection of the louver 213 is tilted with respect to the pixelarrangement direction. For example, the tilt is 20 degrees with respectto the Y-axis direction. Anisotropic scattering structures 631 are alsoformed on the louver 213 on the surface oriented in the +Z direction.However, the longitudinal direction of the anisotropic scatteringstructures 631 coincides with the Y-axis direction, as shown in FIG. 13.As a result, the angle formed by the longitudinal direction of theanisotropic scattering structures 631 and the light-restrictingdirection of the louver 213 is 20 degrees, for example, as shown in FIG.14. Other aspects of the configuration of the present embodiment are thesame as in the aforementioned second embodiment.

In the same manner as in the aforementioned first embodiment, by tiltingthe light-restricting direction of the louver 213 away from the pixelarrangement direction of the liquid crystal panel 7 in the presentembodiment, the arrangement direction of the moiré can be made differentfrom the light-restricting direction of the louver 213. Moreover, theanisotropic scattering structures 631 cause incident light to scatter toa large extent in the arrangement direction of the moiré, withoutcausing significant scattering in the light-restricting direction. Moirécan thereby be reduced without significantly compromising thelight-restricting effects of the louver. As a result, the directivity ofthe light in the frontal direction can be increased, and excellentdisplay quality can be achieved while effectively preventingeavesdropping.

Since the anisotropic scattering effects of the anisotropic scatteringstructures 631 are also symmetrical with respect to the X-axisdirection, it is possible to provide certain compensation for theleft-right asymmetry of the light restricting effects of the louver 213,and to reduce the discomfort caused by the tilted position of thelouver.

Furthermore, in the same manner as in the aforementioned secondembodiment, the thickness of the display device can be reduced since theanisotropic scattering sheet is not provided in the present embodiment.Furthermore, the anisotropic scattering unit, the louver, and thetransmissive liquid crystal panel are optically bonded. Therefore,interference fringes from air layers can be prevented from occurring,and the display quality can be enhanced even further. The louver is alsoprovided on the user side of the display panel, and anisotropicscattering structures are formed in this louver. The user can thereforeeasily attach and detach a louver equipped with an anisotropicscattering structure according to the situation.

A fourth embodiment of the present invention will next be described.FIG. 15 is a perspective view showing the display device according tothe present embodiment; and FIG. 16 is a perspective view showing theanisotropic scattering sheet of the display device shown in FIG. 15. Asshown in FIGS. 15 and 16, the display device 23 according to the fourthembodiment differs from the aforementioned first embodiment in that theanisotropic scattering sheet is a one-dimensional prism sheet 64, andthe anisotropic scattering structures are one-dimensionally arrangedprism structures 641. In the prism sheet 64, the extension direction ofthe prisms coincides with the Y-axis direction. The arrangementdirection of the prisms therefore coincides with the X-axis direction.Other aspects of the configuration of the present embodiment are thesame as in the aforementioned first embodiment.

In the fourth embodiment thus configured, the one-dimensionally arrangedprism structures 641 have scattering effects in one dimension, and thedirection in which the scattering effects are demonstrated is set sothat moiré is reduced. Moiré can therefore be reduced withoutsignificantly compromising the anti-eavesdropping effects, and excellentdisplay quality can be achieved. Compared to the anisotropic scatteringsheet in the aforementioned first embodiment, the scattering has anextremely high degree of anisotropy since there are no scatteringeffects in the longitudinal direction of the prisms. As a result, thereis minimal adverse effect on the light-direction restricting effects ofthe louver. Operations and effects in the present embodiment other thanthose described above are the same as in the aforementioned firstembodiment.

A modification of the fourth embodiment will next be described. FIG. 17is a perspective view showing the anisotropic scattering sheet in thepresent modification. As shown in FIG. 17, a lenticular lens 65 in whichcylindrical lenses 651 as anisotropic scattering structures are arrangedin one dimension is provided as the anisotropic scattering sheet in thepresent modification. In this case, it is sufficient if the cylindricallenses 651 are arranged in the desired direction of scattering effects.For example, in the present modification, the arrangement direction ofthe cylindrical lenses 651 coincides with the X-axis direction, which isthe moiré arrangement direction. The same effects can thereby beobtained as in the aforementioned fourth embodiment. Other aspects ofthe configuration, operations, and effects in the present modificationare the same as in the aforementioned fourth embodiment.

An example was described in the fourth embodiment and modificationthereof in which a prism sheet or lenticular lens is provided separatelyfrom the louver, but the one-dimensionally arranged prism structures 641may be formed directly on the surface of the louver, and the cylindricallenses 651 may also be formed directly on the surface of the louver.

A fifth embodiment of the present invention will next be described. FIG.18 is a sectional view showing the display device according to thepresent embodiment; and FIG. 19 is a sectional view showing thetransparent/scattering state switching element in the display deviceshown in FIG. 18. As shown in FIG. 18, the display device 24 of thepresent embodiment differs from that of the first embodiment in that atransparent/scattering state switching element 122 is provided betweenthe anisotropic scattering sheet 61 and the transmissive liquid crystalpanel 7. Through the switching operation of the transparent/scatteringstate switching element 122 between transparent and scattering states,the display device of the present embodiment can switch between a stateof narrow-angle display for narrowing the angle range of displayvisibility and preventing eavesdropping, and a state of wide-angledisplay for widening the angle range of display visibility and enablinginformation to be viewed by and shared with numerous people at once.Aspects of the configuration of the present embodiment other than thetransparent/scattering state switching element 122 are the same as inthe first embodiment.

Specifically, a light source device 14 is provided to the display device24 according to the present embodiment, and the optical waveguide 3,louver 112, anisotropic scattering sheet 61, and transparent/scatteringstate switching element 122 are provided in sequence in the +Z directionin this light source device 14, and the light source 51 is provided onthe side of the optical waveguide 3. The transmissive liquid crystalpanel 7 is also provided facing the +Z direction of the light sourcedevice 14.

As shown in FIG. 19, a pair of transparent substrates 109 spaced apartfrom each other and arranged parallel to each other is provided to thetransparent/scattering state switching element 122, and electrodes 110are provided to each transparent substrate 109 so as to cover the entiresurfaces that face the other transparent substrate 109. A PDLC (PolymerDispersed Liquid Crystal) layer 111 is provided between the pair oftransparent substrates 109. Liquid crystal molecules 111 b are dispersedin a polymer matrix 111 a in the PDLC layer 111. The PDLC layer 111 isformed, for example, by curing a mixture of a photocuring resin and aliquid crystal material by exposure to light.

The operation of the display device according to the present embodimentthus configured will next be described. In the present embodiment, theoperation until the light emitted from the light source 51 passesthrough the anisotropic scattering sheet 61 is the same as in the firstembodiment. Specifically, light emitted from the light source 51 isemitted in a plane from the light-exiting surface 43 of the opticalwaveguide 3, the directivity of the light in the light-restrictingdirection of the louver 112 is increased, and the light is selectivelyscattered in the X-axis direction in the anisotropic scattering sheet61. The light emitted from the anisotropic scattering sheet 61 is thenincident on the transparent/scattering state switching element 122.

In the transparent/scattering state switching element 122, theorientation state of the liquid crystal molecules 111 b in the PDLClayer 111 is changed by using the pair of electrodes 110 to apply avoltage to the PDLC layer 111 sandwiched between the electrodes. Thetransparent/scattering state switching element 122 thus transmits orscatters incident light without modification, and emits the light to thetransmissive liquid crystal panel 7.

The case of wide-angle display will first be described. In the case of awide-angle display, a voltage is not applied to the PDLC layer 111. Theliquid crystal molecules 111 b are therefore randomly distributed in thepolymer matrix 111 a in the PDLC layer 111, and the incident light isscattered by the liquid crystal molecules 111 b. Accordingly, thehigh-directivity light is uniformly scattered by the PDLC layer 111 anddispersed in a wide range of angles. Specifically, the light whosedirectivity is increased by the louver 112 is scattered by thetransparent/scattering state switching element 122, and becomeswide-angle light having decreased directivity. This light having adistribution that is spread over a wide range enters the transmissiveliquid crystal panel 7, an image is associated with the light, and thelight is emitted without modification as wide-angle light. An image isthus displayed in a wide viewing angle.

A case of a narrow-angle display will next be described. The processuntil the light enters the transparent/scattering state switchingelement 122 is the same in the case of a narrow-angle display as it isin the case of a wide-angle display. In the case of a narrow-angledisplay, a prescribed voltage is applied to the PDLC layer 111. The PDLClayer 111 is thereby placed in a transparent state in which the liquidcrystal molecules 111 b distributed in the polymer matrix 111 a areoriented. As a result, the high-directivity light incident on thetransparent/scattering state switching element 122 is transmittedwithout modification through the transparent/scattering state switchingelement 122. Specifically, the light whose directivity in the lightregulating direction is increased by the louver 112 is emitted from thetransparent/scattering state switching element 122 in a state ofdistribution in which high directivity is maintained. This light havinga distribution of high directivity enters the transmissive liquidcrystal panel 7, an image is associated with the light, and the light isemitted in its original state of high directivity. An image is thusdisplayed in a narrow viewing angle.

In the fifth embodiment thus configured, the moiré created between thelouver and the transmissive liquid crystal display panel is reduced bythe anisotropic scattering sheet, and the display quality is enhanced.Moreover, it is possible to switch between a wide-angle display having awide range of viewing angles that can be viewed by multiple people atonce, and a narrow-angle display having a narrow range of viewing anglesthat is visible only to the user. Other effects in the presentembodiment are the same as in the first embodiment.

An example was described in the present embodiment in which theanisotropic scattering sheet is disposed between thetransparent/scattering state switching element and the louver, but thissequence of arrangement is not necessarily limiting, and the appropriatesequence of arrangement of the components may be changed insofar as thesame effects are obtained. For example, the transmissive liquid crystalpanel, anisotropic scattering sheet, transparent/scattering stateswitching element, and louver may be provided in sequence from the userside. The anisotropic scattering structures may also be formed in thesurface of the louver or transparent/scattering state switching element,as in the second embodiment. Furthermore, the louver and thetransparent/scattering state switching element may be fixed to eachother by an anisotropic scattering adhesion layer.

The liquid crystal panel used in combination with the light sourcedevice of the present invention preferably has minimal dependence on theviewing angle. Contrast inversion during display at a wide viewing anglecan thereby be suppressed. Examples of the mode of such a liquid crystalpanel include IPS (In-Plane Switching), FFS (Fringe Field Switching),AFFS (Advanced Fringe Field Switching), and the like among horizontalfield modes. Vertical alignment modes include MVA (Multi-domain VerticalAlignment), which is multi-domain and possesses reduced viewing-angledependency, as well as PVA (Patterned Vertical Alignment), ASV (AdvancedSuper V), and the like. Furthermore, a film-compensated TN liquidcrystal display panel may also be appropriately used.

The transparent/scattering state switching element is also not limitedto having a PDLC layer, and any element capable of switching between atransparent state and a scattering state may be used. Examples thereofmay include an element that uses a polymer network liquid crystal(PNLC), or an element that uses dynamic scattering (DS). In the presentembodiment, a PDLC layer is used that is in the scattering state when avoltage is not applied, and in the transparent state when a voltage isapplied. The transparent/scattering state switching element thereby nolonger consumes power when in the scattering state. Therefore, the powerthat would have been consumed can be allocated to the backlight source,and the brightness of the light source device during the scatteringstate can be enhanced. It is also possible to use a PDLC layer that isin the transparent state when a voltage is not being applied, and in thescattering state when a voltage is applied. This type of PDLC layer canbe obtained by exposing a mixture of a photocuring resin and a liquidcrystal material to light and curing the mixture while applying avoltage. There is thereby no need for applying a voltage to the PDLClayer, and power consumption can be suppressed in a mobile informationterminal in which narrow-angle display is frequently used. Cholestericliquid crystal, ferroelectric liquid crystal, or the like may also beused as the liquid crystal molecules for the PDLC layer. Even whenvoltage is no longer applied, these liquid crystals retain theorientation they had when the voltage was applied, and have memoryproperties. By using this type of PDLC layer, it becomes possible toreduce power consumption.

A sixth embodiment of the present invention will next be described. FIG.20 is a sectional view showing the display device according to thepresent embodiment. As shown in FIG. 20, the display device 25 of thepresent embodiment differs from that of the fifth embodiment in that ananisotropic scattering sheet is not provided, and thetransparent/scattering state switching element 222 instead hasanisotropic scattering properties. Specifically, the scattering in theX-axis direction by the transparent/scattering state switching element222 is more significant than in the Y-axis direction at least in thetransparent state. This type of transparent/scattering state switchingelement 222 can be formed using a polymer network liquid crystal (PNLC)layer in which the ratio of the polymer and the liquid crystal variesbetween the Y-axis direction and the X-axis direction, for example. Thetransparent/scattering state switching element 222 may also be composedof a PDLC layer in which liquid crystal droplets are narrowly extendedin the Y-axis direction in the polymer. Other aspects of theconfiguration of the present embodiment are the same as in the fifthembodiment.

The operation of the display device according to the present embodimentthus configured will next be described. FIG. 21 is a graph showing thevoltage dependency of the haze of the PNLC layer in the X- and Y-axisdirections, wherein the voltage applied to the PNLC layer is plotted onthe horizontal axis, and the haze (HAZE: haze value) of the PNLC layeris plotted on the vertical axis. As shown in FIG. 21, the haze of thePNLC layer is highest during no voltage application both in the X-axisdirection and in the Y-axis direction, and the haze decreases as theapplied voltage is increased. The absolute value of the haze is higherin the X-axis direction than in the Y-axis direction over the entirerange of voltages. Specifically, the degree of scattering is greater inthe X-axis direction than in the Y-axis direction regardless of thevoltage applied.

In the present embodiment, the transparent/scattering state switchingelement 222 scatters light mainly in the X-axis direction. Therefore,moiré arranged in the X-axis direction created between the louver andthe pixels of the transmissive liquid crystal panel can be obscuredwithout significantly compromising the light-direction restrictingeffects of the louver 112. In the display device according to thepresent embodiment, it is possible to freely switch between wide-angledisplay and narrow-angle display, moiré that occurs particularly duringnarrow-angle display can be reduced, and the display quality can beenhanced. Since the transparent/scattering state switching elementfunctions as an anisotropic scattering element in the display device ofthe present embodiment, there is no need to provide an anisotropicscattering sheet or the like, and slim profile and low cost can beachieved.

The present invention can be suitable for use as the display device of amobile telephone, a PDA, a gaming device, a digital camera, a videocamera, a video player, a notebook-type personal computer, or othermobile terminal device, and as the display device of a cash dispenser, avending machine, a monitor, a television receiver, or other fixed-mountterminal device.

1. A display device comprising: a display panel in which a plurality ofpixels are arranged in a matrix; a light-direction restricting elementwhich is interposed in the path of the light incident on the displaypanel or the light exiting from the display panel, and which is providedwith a plurality of transparent areas and a plurality of light-absorbingareas arranged in alternating fashion in a first direction that differsfrom the arrangement direction of said pixels; and anisotropicscattering unit for scattering incident light to a greater degree in thearrangement direction of moiré created between said display panel andsaid light-direction restricting element than in said first direction.2. The display device according to claim 1, wherein the direction ofmaximum scattering by said anisotropic scattering unit is one directionamong the arrangement directions of said pixels.
 3. The display deviceaccording to claim 1, wherein the direction of maximum scattering bysaid anisotropic scattering unit is the direction orthogonal to saidfirst direction.
 4. The display device according to claim 1, whereinsaid display panel, said light-direction restricting element, and saidanisotropic scattering unit are arranged in sequence along said lightpath.
 5. The display device according to claim 1, wherein said displaypanel, said anisotropic scattering unit, and said light-directionrestricting element are arranged in sequence along said light path. 6.The display device according to claim 1, wherein said light-directionrestricting element, said anisotropic scattering unit, and said displaypanel are arranged in sequence along said light path.
 7. The displaydevice according to claim 1, comprising a planar light source foremitting said light in a plane.
 8. The display device according to claim1, wherein said anisotropic scattering unit comprises a transparentsubstrate; and a convex portion which extends in one direction and isformed on the surface of the transparent substrate.
 9. The displaydevice according to claim 8, wherein said anisotropic scattering unit isa one-dimensionally arranged prism sheet in which a plurality of prismsextending in one direction are arranged parallel to each other.
 10. Thedisplay device according to claim 8, wherein said anisotropic scatteringunit is a lenticular lens in which a plurality of cylindrical lensesextending in one direction are arranged parallel to each other.
 11. Thedisplay device according to claim 1, wherein said anisotropic scatteringunit comprises a transparent substrate; and a concave portion whichextends in one direction and is formed on the surface of the transparentsubstrate.
 12. The display device according to claim 1, wherein saidanisotropic scattering unit is a convex portion formed on the surface ofsaid light-direction restricting element or the surface of said displaypanel.
 13. The display device according to claim 12, wherein saidanisotropic scattering unit is a one-dimensionally arranged prismstructure in which a plurality of prisms extending in one direction arearranged parallel to each other.
 14. The display device according toclaim 12, wherein said anisotropic scattering unit is a lenticular lensstructure in which a plurality of cylindrical lenses extending in onedirection are arranged parallel to each other.
 15. The display deviceaccording to claim 1, wherein said anisotropic scattering unit is aconcave portion formed on the surface of said light-directionrestricting element or the surface of said display panel.
 16. Thedisplay device according to claim 1, wherein said anisotropic scatteringunit is an anisotropic scattering adhesion layer for affixing saidlight-direction restricting element to said display panel.
 17. Thedisplay device according to claim 1, wherein said anisotropic scatteringunit is disposed inside said display panel.
 18. The display deviceaccording to claim 17, wherein said display panel has an optical film,and said anisotropic scattering unit is an anisotropic scatteringadhesion layer for fixing said optical film to the substrate of saiddisplay panel.
 19. The display device according to claim 1, comprising atransparent/scattering state switching element which is capable ofswitching between a state for transmitting incident light and a statefor scattering the light, and which is interposed in the path of thelight that is incident on said display panel.
 20. The display deviceaccording to claim 19, wherein said anisotropic scattering unit is ananisotropic scattering adhesion layer for affixing saidtransparent/scattering state switching element to said light-directionrestricting element.
 21. The display device according to claim 1,wherein said display panel is a liquid crystal panel.
 22. The displaydevice according to claim 21, wherein said liquid crystal display panelis a liquid crystal display panel that operates on a lateral fieldprinciple, a multi-domain vertical alignment principle, or afilm-compensated TN principle.
 23. A display device comprising: alight-direction restricting element provided with a plurality oftransparent areas and a plurality of light-absorbing areas arranged inalternating fashion in a first direction; a transparent/scattering stateswitching element capable of switching between a state for transmittingthe light incident from the light-direction restricting element and astate for scattering the light; and a display panel which displays animage by transmitting the light incident from saidtransparent/scattering state switching element, and in which a pluralityof pixels are arranged in a matrix in a direction that differs from saidfirst direction; wherein said transparent/scattering state switchingelement scatters incident light to a greater degree in the arrangementdirection of moiré created between said display panel and saidlight-direction restricting element than in said first direction when insaid light-transmitting state.
 24. The display device according to claim23, wherein said display panel is a liquid crystal panel.
 25. Thedisplay device according to claim 24, wherein said liquid crystaldisplay panel is a liquid crystal display panel that operates on alateral field principle, a multi-domain vertical alignment principle, ora film-compensated TN principle.
 26. A terminal device comprising thedisplay device according to claim
 1. 27. The terminal device accordingto claim 26, wherein the direction of maximum scattering of light bysaid anisotropic scattering unit is the direction perpendicular to thescreen of said terminal device.
 28. A terminal device comprising thedisplay device according to claim
 23. 29. The terminal device accordingto claim 28, wherein the direction of maximum scattering of light bysaid transparent/scattering state switching element is the directionperpendicular to the screen of said terminal device when saidtransparent/scattering state switching element is in saidlight-transmitting state.
 30. The terminal device according to claim 26,comprising a mobile telephone, a personal information terminal, a gamingdevice, a digital camera, a video camera, a video player, anotebook-type personal computer, a cash dispenser, or a vending machine.31. The terminal device according to claim 28, comprising a mobiletelephone, a personal information terminal, a gaming device, a digitalcamera, a video camera, a video player, a notebook-type personalcomputer, a cash dispenser, or a vending machine.
 32. A light sourcedevice comprising: a planar light source for emitting light in a plane;a light-direction restricting element which is interposed in the path ofsaid light and which is provided with a plurality of transparent areasand a plurality of light-absorbing areas arranged in alternating fashionin a first direction; and anisotropic scattering unit for scatteringincident light to a greater degree in a direction other than said firstdirection.
 33. The light source device according to claim 32, whereinthe light-emitting surface of said planar light source has a rectangularshape, and the direction of maximum scattering by said anisotropicscattering unit is parallel to the extension direction of an arbitraryside of said rectangle.
 34. The light source device according to claim32, wherein the direction of maximum scattering by said anisotropicscattering unit is the direction orthogonal to said first direction. 35.The light source device according to claim 32, wherein said planar lightsource, said light-direction restricting element, and said anisotropicscattering unit are arranged in sequence.
 36. The light source deviceaccording to claim 32, wherein said anisotropic scattering unitcomprises a transparent substrate; and a convex portion which extends inone direction and is formed on the surface of the transparent substrate.37. The light source device according to claim 36, wherein saidanisotropic scattering unit is a one-dimensionally arranged prism sheetin which a plurality of prisms extending in one direction are arrangedparallel to each other.
 38. The light source device according to claim36, wherein said anisotropic scattering unit is a lenticular lens inwhich a plurality of cylindrical lenses extending in one direction arearranged parallel to each other.
 39. The light source device accordingto claim 32, wherein said anisotropic scattering unit comprises atransparent substrate; and a concave portion which extends in onedirection and is formed on the surface of the transparent substrate. 40.The light source device according to claim 32, wherein said anisotropicscattering unit is a convex portion formed on the surface of saidlight-direction restricting element.
 41. The light source deviceaccording to claim 40, wherein said anisotropic scattering unit is aone-dimensionally arranged prism structure in which a plurality ofprisms extending in one direction are arranged parallel to each other.42. The light source device according to claim 40, wherein saidanisotropic scattering unit is a lenticular lens structure in which aplurality of cylindrical lenses extending in one direction are arrangedparallel to each other.
 43. The light source device according to claim32, wherein said anisotropic scattering unit is a concave portion formedon the surface of said light-direction restricting element.
 44. Thelight source device according to claim 32, comprising atransparent/scattering state switching element which is capable ofswitching between a state for transmitting incident light and a statefor scattering the light, and which interposed in the path of the lightemitted by said planar light source.
 45. The light source deviceaccording to claim 44, wherein said anisotropic scattering unit is ananisotropic scattering adhesion layer for affixing saidtransparent/scattering state switching element to said light-directionrestricting element.
 46. A light source device comprising: a planarlight source of emitting light in a plane; a light-direction restrictingelement which is interposed in the path of said light and which isprovided with a plurality of transparent areas and a plurality oflight-absorbing areas arranged in alternating fashion in a firstdirection; and a transparent/scattering state switching element capableof switching between a state for transmitting the light incident fromthe light-direction restricting element and a state for scattering thelight; wherein said transparent/scattering state switching elementscatters incident light to a greater degree in a direction other thansaid first direction when in said light-transmitting state.
 47. Anoptical member comprising: a light-direction restricting elementprovided with a plurality of transparent areas and a plurality oflight-absorbing areas arranged in alternating fashion in a firstdirection; and anisotropic scattering unit which scatters incident lightto a greater degree in a direction other than said first direction andwhich is integrally formed in the surface of the light-directionrestricting element.
 48. The optical member according to claim 47,wherein the external shape of said light-direction restricting elementis rectangular, and the direction of maximum scattering by saidanisotropic scattering unit is parallel to the extension direction of anarbitrary side of said rectangle.
 49. The optical member according toclaim 47, wherein the direction of maximum scattering by saidanisotropic scattering unit is the direction orthogonal to said firstdirection.
 50. The optical member according to claim 47, wherein saidanisotropic scattering unit is a convex portion formed on the surface ofsaid light-direction restricting element.
 51. The optical memberaccording to claim 47, wherein said anisotropic scattering unit is aconcave portion formed on the surface of said light-directionrestricting element.
 52. The optical member according to claim 47,wherein said anisotropic scattering unit is a one-dimensionally arrangedprism structure in which a plurality of prisms extending in onedirection are arranged parallel to each other.
 53. The optical memberaccording to claim 47, wherein said anisotropic scattering unit is alenticular lens structure in which a plurality of cylindrical lensesextending in one direction are arranged parallel to each other.
 54. Theoptical member according to claim 47, wherein said anisotropicscattering unit is an anisotropic scattering adhesion layer.
 55. Theoptical member according to claim 47, comprising atransparent/scattering state switching element capable of switchingbetween a state for transmitting incident light and a state forscattering the light.
 56. The optical member according to claim 55,wherein said anisotropic scattering unit is an anisotropic scatteringadhesion layer, and said light-direction restricting element and saidtransparent/scattering state switching element are affixed to each otherby the anisotropic scattering adhesion layer.
 57. An optical membercomprising a light-direction restricting element which is provided witha plurality of transparent areas and a plurality of light-absorbingareas arranged in alternating fashion in a first direction, and whichscatters incident light to a greater degree in a direction other thansaid first direction when in said light-transmitting state.